Wall tube fluid heater with a releasably anchored enclosure



July 1, 1958 F. s. TOLLOW 2,841,122

WALL TUBE FLUID HEATER WITH A RELEASABLY ANCHORED ENCLOSURE Filed March 12, 1953 3 F|G.4 F|G.2

H INVENTOR frecg rick S 7Z//on ATTORNEY United States Patent WALL FLUID HEATER WITH A RELEAS- ABLY ANCHORED ENCLOSURE Frederick S. Tollow, South Croydon, England, assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application March 12, 1953, Serial No. 342,005

4 Claims. (Cl. 122-6) My invention relates to fluid heater walls and more particularly to an improved means of attaching wall forming materials and structures to the tubes of such fluid heaters.

In fluid heaters, such as steam boilers, for example, the wall heating tubes form the structural nucleus about which the outside wall forming materials andstructures are attached. Refractory brick, insulation, and casings and occasionally such structures as secondary air chambers, are secured to thesetubes by metallic anchoring elements which are welded directly to the fluid heating tubes. It has been found that where the boiler becomes subject to an abnormally high internal pressure, which would occur if there were an explosion in the furnace for example, this high pressure would force the wall forming materials out, pulling the anchoring elements with them with resulting damage to the fluid heating tubes. These connecting elements, welded to the tubes are then apt to pull the tubes out of alignment and in some cases disrupt the metal of the tubes.

In accordance with my invention I have welded the anchoring elements directly to the tubes and purposely made the connection formed by these elements weak so that they will fail in tension before the occurrence of an internal furnace pressure suflicient to pull tubes out of line or damage the tube metal.

It is an object of my invention to provide an exterior wall securing means welded to the tubes of a heat exchanger which will fail under a tensile force low enough to prevent either tube misalignment or tube damage.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a specific embodiment of my invention.

Of the drawings:

Fig. 1 is a horizontal section of a steam boiler wall constructed in accordance with my invention;

Fig. 2 is an enlarged view of the tube attached anchoring nut shown in Fig. 1;

Fig. 3 is an enlarged vertical section of the anchoring nut shown in Fig. 1 showing the flux head, the sawcut, and the rolled threads; and

Fig. 4 is a horizontal view of the anchoring nut shown in Fig. l.

The fluid heater wall constructed in accordance with my invention cooperates with other walls of similar construction to define a furnace adapted to contain heating gases generated by the burning of a fuel in the furnace and includes a multiplicity of wall tubes with anchoring elements disposed thereon, preferably on 18" horizontal centers and 24" vertical centers. Each set of anchoring connections includes a nut 11 having diametrically opposite longitudinal sawcuts or slits extending to,

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or substantially to, the base parts of the nuts and a stud 12. Each stud 12 has threads, preferably rolled on both ends and at a center portion, with one end threaded into the nut 11. A heat resisting stratum is disposed along the backs of the tubes. This may consist of refractory brick 13 held in place by an intermediate spiral nut 18 which is'threaded on to the center portion of the stud. The layers of additional insulation 14 are held in proper position outside the refractory brick 13 by the outside spiral nuts 19 threaded on the outside portions of the studs. 17 is a stratum of hard setting cement applied to the wall outside the additional (or slab) insulation and is preferably re-enforced by expanded metal (or its equivalent) 26 held in place by the spiral nuts 19. A casing 17 may be connected to the wall using similar connecting elements (not shown) and slightly spaced from the hard setting cement leaving an air space 16.

Each set of anchoring elements used to secure the wall forming means such as refractory brick, insulation, and casings, includes a nut that is purposely weakened by diametrically opposite longitudinal sawcuts in the threaded portion down to the base of the threaded portion or sub- 'stantially to said base, and a stud threaded into this nut. The sawcuts 23 on the nut 11 as shown in Figs. 2, 3 and 4 are cut to, or substantially to, the base 21 of the threads, the depth of cut being determined by the strength of the connection that is desired. The nut 11 is constructed with a steel cap 22 containing a charge of flux 24 to facilitate gun welding of the nuts to the tubes.

During operation of the fluid heater, if an abnormal internal pressure such as an explosion occurs which would blow the wall forming materials outwardly from the tubes the wall anchoring means would fail before the outward movement of the wall forming materials could pull the tubes out of line or damage the metal of the tubes. The effect of weakening the nut 11 by cutting the slits 23 into it causes the opposite halves of the nut to move outwardly until the studs 12 become disengaged from the nut. The force at which this will occur may be varied by changing the size of the cuts and the deepness of penetration. In some instances the illustrative releasable connection is advantageously formed by using rolled threads in the nut or on the stud, or on both, to facilitate and control the release point of the anchoring elements.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features What is claimed is:

1. In a fluid heater, walls defining a furnace adapted to contain heating gases generated by the burning of a fuel in said furnace, transversely spaced fluid heating furnace wall tubes, said walls having gas-tight components disposed at the outer side of said tubes and having portions of said components between said tubes exposed to heating gas pressure, and anchoring devices each comprising a pair of elements and securing means associated with one of said elements and cooperating with said elements to maintain said wall components in place, the other of said elements being connected at one end to one of said wall tubes and disengageably connected at its opposite end to said one element at a position between said one wall tube and said securing means, the connection between said elements being constructed to yield before said wall tube connection upon the application of an undue strain on said elements and so that the 3 portion of the wall components between the wall tubes and the connection of said elements may move freely past the connection between said elements in a direction away from said wall tubes when the connection between said elements yields.

2.111 a fluid heater, walls defining a furnace adapted to contain heating gases generated by the burning of a fuel in said furnace transversely spaced fluid heating furnace wall tubes, said walls having gas-tight components disposed at the outer side of saidtubes and having portions of said components between said tubes exposed to heating gaspressure, and anchoring devices each comprising a pair of elements'and securing means associated with one of said elements and cooperating with said elements to maintain said wall components in place, the other of said elements being connected at one end to one of said wall tubes and 'disengageably connected at its opposite end to said one element at a position between said one wall tube and said securing means, one of said elements being formed with at least one slot at the connection to the other element so that the connection between said elements will yield before said wall tube connection upon the application of an undue strain on said elements, the connection between said elements being arranged so that the portion of the wall components between the wall tubes and the connection of said elements may move freely past the connection between said elements in a direction away from said wall tubes when the connection between said elements yields.

3. In a fluid heater, walls defining a furnace adapted to contain heating gases generated by the burning of a fuel in said furnace, transversely spaced fluid heating furnace wall tubes, said walls having gas-tight components disposed at the outer side of said tubes and having portions' of said components between said tubes exposed to heating gas pressure, and anchoring devices each comprising a nut, a stud and securing means associated with said stud and cooperating with said nut and stud to maintain said wall components in place, said nut being connected at one end to one of said wall tubes and threadable connected at its opposite end to said stud at a position between said one wall tube and said securing means, said out being formed with slots so that the connection between said nut and stud will yield before said wall tube connection upon the application of an undue strain on said nut and stud, the connection between said nut and stud being arranged so that the portion of the wall components between the wall tubes and the connection of said nut and stud may move freely past the connection between said nut and stud in a direction away from said wall tubes when the connection between said nut and stud yields.

4. In a fluid heater, walls defining a furnace adapted to contain heating gases generated by the burning of a fuel in said furnace, transversely spaced fiuid heating furnace wall tubes, said walls having gas-tight components disposed-at the outer side of said tubes and having portions of said components between said tubes exposed to heating gas pressure, and anchoring devices each comprising an.internally threaded nut, a stud and securing means associated with said stud andcooperating with said nut and stud to maintain said Wall components in place, said nut being connected at one end to one of said wall tubes and threadably connected at its opposite end to said stud at a position between said one wall tube and said securing means, said nut being formed with longitudinal slots extending through its threaded portion and open at said opposite end of said nut so that the connection between said nut and stud will yield before said wall tube connection upon the application of an undue strain on said nut and stud, the connection between said nut and stud being arranged so that the portion of the Wall components between the wall tubes and the connection of said nut and stud may move freely past the connection-between saidnut and stud in a direction away from said wall tubes when the connection between said nut and stud yields.

References'Cited'in the file of this patent UNITED STATES PATENTS 1,092,256 Glauber Apr. 7, 1914 1,523,463 Thomson -e Jan. 20, 1925 1,677,887 Bradford July 24, 1928 1,959,866 Jacobus May 22, 1934 2,018,455 Lofton Oct. 22, 1935 2,042,953 McArdle et al June 2, 1936 2,268,416 Nelson Dec. 30, 1941 2,426,653 Whelan Sept. 2, 1947 2,536,039 Craven Jan. 2, 1951 2,656,902 Gotshall Oct. 27, 1953 FOREIGN PATENTS 31,207 Switzerland Feb. 15, 1904 486,257 Great Britain June 1, 1938 

